High temperature plasmas and various other sources emit x-rays. Spectroscopy provides means for classifying such radiations and makes it possible to determine atoms, ions and level transitions involved. It would be of great value to be able to carry out such determinations with spatial resolution in a simple and convenient manner by comparatively simple means.
Hitherto rather cumbersome and complicated means have been resorted to for x-ray measurements with spatial resolution. Spectroscopy has never been carried out in such manner as to result in both good spatial and energy resolution. Soller slit systems have been used in x-ray and astrophysical spectroscopy. Such systems are complicated, wasteful of energy as much of the radiation is blocked, comparatively expensive and result only in a very limited partial spatial resolution. High resolution curved x-ray spectrometers are described by Johansson in Z. Physik, 82,507 (1933), but these do not provide means for attaining a spatial resolution.
The effect of double reflections, also known as simultaneous reflections, is known in crystollagraphy, as for example from the articles of Renninger, Z. Physik, 106, 141 (1937) and Fraenkel, Bull. Res. Counc. Israel, 6A, 125 (1957) and Rev. Sc. Instr., 29, 726 (1958). The latter references disclose that at least single diamond, germanium and silicon crystals are capable of such double reflections. This effect was described as a scientific curiosity and no use has been hitherto for the applicative nature of this phenomenon.